Final Floor Replacement Technique

[malconium]

Yesterday I found a plastic panel material that was in stock locally that was almost perfect for AS floor replacement. It is $57.20 per 3/4" x 4' x 8' sheet and it is virtually indestructable. The catch (and it is a big one) is that it is not stiff enough. I do not know how it compares to the CoDeMo panels as far as stiffness but it is sure floppy. When you let about 3' of a sheet of 3/4" plywood overhang the stack it basically sticks out straight. This stuff sags 6 to 12". Anyway you can take a look at the information about the product at the following web site:

www.newcityresources.com

The product is called Polyboard. Some of you reading this might have other uses for it besides for your AS floor. I can think of some other uses.

The material is not billed as being a structural material. The "General Installation" tab is the only place I could find where it talked about span distances in horizontal uses. It said there not to exeed 500~600 lbs load carrying weight. It also said that supports should be at a minimum of 12 centers to prevent deflection. Yes, It did say "12" too without any units mentioned. I assume that they meant inches but who knows. I do not understand enough about the structural details in their chart in the brochure I picked up to know what the deflection numbers mean. Maybe someone reading this could comment and perhaps compare it to plywood? The table said the following about the material:

dimensional stability - load deflection = 1.42 * 10-2 of span (the -2 is the negative power of)

I could envision adding additional support so that the maximum span was 10 or 12 inches if that would work. What I would be more concerned about though is the issue of how much structural support is the plywood actually providing (and needing to provide) to the bottom of the walls along the sides of the AS. My observation is that the plywood must be working with the outriggers to help support the bottom of the walls. That is likely to be one reason the original plywood was installed cross wise to the frame for more support to the ends of the outriggers. I guess I could envision doing something to beef up the support for the outriggers too. I just don't know how much extra support would be required and just where. Of course extra support adds to the cost of the solution along with the extra work involved.

If the support problem could be resolved this material seems like it would be really great.

Malcolm

[malconium]

At the same plastics supplier (GE Polymershaps) where I found the Polyboard I discussed other options. They carry King Plastics Starboard. It is pretty expensive but is not too bad otherwise. The weight is more than plywood which is a down side (about 50% more) but it is billed as a replacement for marine grade plywood in harsh outdoor marine applications. Sheet sizes that GE stocked were 54" x 96" for $215 per sheet. They did offer an alternative which sells for $145 per 4' x 8' sheet though. This stuff is supposedly pretty much the same as Starboard except that it does not have UV enhibitors added (which accounts for the higher cost of Starboard). The stuff is called "Sanalite" and is primarily offered as a cutting board material. I was told that the composition was virtually identical to Starboard except for the UV part. It is made mostly out of polyethelene. It could be a good choice if one could live with the extra weight and couled afford the $145 per sheet price. In my case I would need 7 sheets which adds up pretty fast.

Malcolm

[markdoane]

Malcolm,

I looked at this stuff a year ago and decided it was out of my price range. I would really like to see you try it, it sounds like the 'ultimate' solution you are looking for.

[malconium]

Don,

Just to be clear you are referring to my second posting about the Sanalite panels arn't you? Did you find that that the structural values were indeed inline with what is needed?

Thanks,

Malcolm

[markdoane]

No, I was looking at the Starboard. I didn't go through the calculations because the $$ were prohibitive. When I saw the Sanalite was polyethylene I kind of ignored it. I think polypropylene might be a better, althought we don't know exactly what the Starboard is. It might just be PE with a little calcium carbonate in it. I tend to be skeptical if a manufacturer won't say what their product is made of.

Need to keep in mind that an ultimate floor can still fail. I would hate to design and put in a 100+ year floor, and get run into by a bus on your first trip.

Also, you need to figure out what you want to use for flooring. Could be tough to find a mastic that will stick to PE. You may need to overlay with a Pergo type floor or carpet. Also need to figure out how to anchor all the floor mounted casework. Just a few things to keep in mind.

[Bob Thompson]

Now you guys are starting to make me nervous. Be very cautious about using carbon fiber anything! Carbon fiber is very electrolytically active (unfortunately it doesn't typically show up on a galvanic chart) and will cause the destruction of just about anything metal that comes in pure contact with it. In panel form, the carbon fiber is typically separated from metals by a layer of fiberglass or other fiber material. However, when it comes time to anchor walls, etc. and drilling screws into the the floor panels, the carbon fiber will cause corrosion of the fasteners.

Now for aluminum honeycomb panels. I've used them to make tonneau covers. To be able to do anything with these panels, you must first put an aluminum channel completely around the perimeter and bed it in with autobody epoxy. With the perimeter channel in place you can now mount screws, hinges, etc. to the channel to secure the panel. In the honeycomb panel "field" (as in not along the perimeter) you will have great difficulty mounting anything as there is not enough material to get a screw to bite into and hold. In airplanes, they use backer plates, etc. It won't be easy to secure walls and cabinets in your Airstream. That's the simplistic beauty of plywood floor decking. You can screw things to it.

To evaluate how stiff a plywood is going to be, you want to look at its rated Fiber Bending Stress (Fb). Modulus of elasticity isn't as effective for strength comparisons. The higher the Fb the proportionally stiffer the product. If you want to use a less stiff product because it is more durable, decrease the free unsupported distance between supports to reduce sag under load. You can do this by either spacing the supports closer together or by making the bearing surface at the supports wider (screw a bearing plate to the top of your "C" channels. With a stiffer product (higher Fb) you can space supports farther apart.

Now to get down to business. Unless you are building your trailer as a piece of sculpture and art, fore go the aluminum flooring and use the marine plywood. If you want it to last a very long time you can do one of a few things to the plywood. You can treat it with wood preservative like Olympic Stain Wood Preservative, you can encapsulate each piece by coating it with three coats of West System Epoxy (or similar epoxy) applied with a foam roller, or you can seal it completely so no moisture can penetrate by using boiled linseed oil mixed with mineral spirits to completely saturate the wood until it will absorb no more. Making sure water either cannot get into the wood or cannot do damage if it does get in is the key.

Enjoy!

[Johndigbydog]

I agree with the ply replacement. The aluminum route seems to be severe overkill and a lot of money, properly treated ply and a properly sealed wall to exterior are paramount. John